“There’s some social science research that suggests that women are generally more emotionally expressive than men. So the finding that women use more emoticons is not horribly surprising.”

The study found that women used emoticons twice as often when texting. But it also found – more surprisingly – that when men did use emoticons, they used a greater variety of them.

Kortum says he has no idea why that is the case. But he has some ideas that could be tested in the future:

“One thing it could be is that men feel the need to use a wider variety because they have less confidence in the content of the text message, that the content of the text message is conveying the emotion that they want to. So they might stretch a little further in their vocabulary of emoticons to make sure that that message comes through. We don’t really know.”

The findings don’t apply to email or instant messages, but only reflect what happened during texting.

Kortum says only four percent of the texts in the study even used emoticons. That may be because people tend to text people they already know fairly well.

In other digital formats, emoticons may help even more to ensure that a stranger understands when you are being funny or sarcastic.

Kortum says this study and others like it may be used to design better smartphones.

For example:

“It might be advantageous to build the top one or two emoticons into a keyboard. If the device knew that I was in text message mode, it might provide me with two more keys, the top two emoticons used, so that I could include those into my messages in the least painful way.”

But in addition to better phones, Kortum wants to learn more about how humans communicate emotionally in the digital age.